In hole hammers are generally used for boring in gravelly and stony grounds, especially for operation in stone. In such use the hammer is held in compression from behind by the boring rod and is continually rotated.
The pressure medium, generally pressurized air, enters from behind into the hammer and moves the striking piston in the interior of the hammer. The striking piston impacts onto the workhead, for example a boring crown which is not rigidly connected with the housing but which is guided by a splined shaft rotatably fixed but lengthwise shiftable in the housing. This spline must be relatively long so that high rotation moments can be stably transmitted along with simultaneous dynamic blows. Correspondingly, customary in hole hammers are relatively long, as the longitudinal shiftability between the housing and the boring crown must be assured. The boring crown itself is, because of its length, relatively heavy and expensive. Since the boring crown is a wear part and frequently has to be exchanged, this leads to relatively high operating costs for the drive of the in hole hammer.
The invention has as its basic object the provision of a relatively short compact in hole hammer by means of which the costs for the workhead can be reduced.